For intelligent traffic systems, VGA resolution CCD-based cameras have traditionally been the accepted technology, but with the quality of CMOS image sensors continuously improving, CMOS-based cameras are now a viable option for demanding license plate recognition applications. The latest system requirements are for higher resolution (HDTV) and frame rates of 30 to 60 frames per…
Intelligent Transportation Systems (ITS) are constantly becoming more sophisticated and one recent trend is the increased use of machine vision cameras. We at Adimec have several new customers and many more inquiries to use our cameras in intelligent traffic systems, primarily high speed license plate recognition applications for now. Some other traffic applications for our…
The latest machine vision camera technology can allow for improvements in intelligent traffic system (ITS) performance to minimize detection time in case of accidents, increase the detection rates in cases of violations, and minimize overall costs from police time and traffic jams. With decreasing budgets, these systems also need to maintain reasonable costs and prove…
Video camera-based intelligent transportation systems (ITS) are a broad category from automobile sensing systems, traffic management systems, toll collection systems, and more. ITS can be further broken down into those using automatic license plate recognition (ALPR) or automatic number plated recognition (ANPR).
OCR algorithms work better with high quality images for accurate Automated License Plate Recognition ALPR
Unlike what is shown on TV, you cannot zoom into a blurry image and expect to get more details. An image with acceptable sharpness and contrast must be acquired with the appropriate system from the start. This means the right image sensor, camera, optics, and lighting all combined in a reliable way.
Sharpness of the image is one important component that influences the accuracy of ALPR systems Especially in high speed ALPR systems such as open road tolling, it can be a challenge to get the required sharpness.
Matrox has written a concise white paper providing details on CoaXPress and help when consideriing CoaXPress versus Camera Link or GigE Vision for your vision system.
Now that you have done what is possible to get a sharp image for your OCR algorithm for automatic license plate recognition, another image quality parameter that is critical is contrast.
Usable images for ALPR are sharp, contrast rich and without artifacts. Reducing image sensor artifacts is probably the most difficult thing to do, but here are some artifacts that camera manufacturers can help to remove or minimize that are specific to the needs of ALPR:
Since automatic license plate recognition (ALPR) or automatic number plate recognition (ANPR) relies on optical character recognition (OCR) of images, it makes sense that a higher quality input image results in higher accuracy.